Calculating machine



Sept, 2, 1958 B. D. sMlTH CALCULATING MACHINE Filed March 2, 1955 3 Sheets-Sheet 1 INVENTOR BLANCHARDy D. SMITH Sept. 2, 1958 B. D. sMl'rH CALCULATING MACHINE 5 Sheets-Sheet 2 Filed March 2, 1955 INVENTOR lSMITH BLANCHARD D.

wadum WVM l l ATTORNEY Sept. 2, 1958 B. D. SMITH CALCULATING MACHINE 5 Sheets-Sheet 5 Filed March 2, 1955 INVENTOR BLANCHARB D. SMBTH United States Patent O CALCULATING MACHINE BlanchardD. Smith, Atlanta, Ga. Application March 2, 1955, Serial No. 491,664

9 Claims. ((1235-59) This rapplication is a y l ity of numeral wheels, each numeral wheel having associated therewith a column of depressible keys whereby the numeral wheel may be actuated to enter a desired digit in the machine. The mechanism whereby, upon depression ofk a key in a particular column of keys,` av particular digit is entered into the machine tends to be complex particularly where the mechanism is capable of rotating the numeral wheel selectively in one direction yor the other to enable both addition and direct subtraction to be performed by the machine. Furthermore, actuating 4mechanisms known in the art tend to move rather forcibly f thereby producing undesirable impacts which, in turn, increase wear and tear in the machine during its operation.

The present invention is therefore directed to the problem of providing a numeral wheel actuating mechanism for a calculating machine which is less. complicated than the generally complex mechanisms utilized for such a purpose but which is nevertheless positive in its operation and smooth in operation in the sense that movements of the mechanism are smoothly decelerated so as to avoid undesirable impacts. In the solution of this problem,fthe vpresent invention provides a numeral wheel actuating mechanism which is capable of actuation for addition and for direct subtraction and one which is more inexpensive to manufacture than conventionaltypes of actuating mechanisms now known in the art,

Itis therefore an object of the present invention to provide a new and improved numeral wheel actuating mechanism for a calculating machinewhich is less complicated than usual mechanisms of such type now known, is positive in operation, and is relatively inexpensive to manufacture.

It is another object of the present invention topro- `vide such actuating mechanism which is capable of operation for addition and for direct subtraction.

It is a further object of the present invention tovprovide such a mechanismwhich, although positive in action, is nevertheless smooth in operation so as to avoid undesirable impacts which adversely affect the life of 4such apparatus.

These, and other objects are achieved in Aan actuating mechanism in which the numeral wheel driving gear is directly driven by a sector gear which is mounted for both rotatable and axial movement relative to the numeral wheel. The sector gear drives the numeral wheel by direct engagement with a numeral wheel driving gear which is coupled to a rotatably supported -numeral wheel. The sector gear is driven by a driving memberwhich in turn is actuated by suitable mechanism upon the depression of a key. Asingle complete` actuation of akey causes the driving memberto engagethesector'gear' to v in `its rest position.

2,850,230 Patented Sept.- 2, 1958 ICC rotate the sector gear from its rest position to a position dependent upon the numerical value of the key actuated andthen to drive the sector gear rotatably `back/to the .rest position. A predetermined amount of lost` motion between the driving member and the sector geart is present duringt-he initial portion of both the forward and return str okeof the drivingmember.

Cooperating cam means'are Vprovided onfthe sector y.gear and drivingmember which cause anaxial tilting movement'ofthe ysector gear to takeplace during both lost motion portions of the movement of the driving member. The axial tilting movement shifts thesector lgearbetween a iirst planein whihthe sectongear Y. is in mesh with the numeral wheel driving gear and a second plane in which the sector gear is out of mesh with the numeral wheel -driving gear.

Thus, for a single complete operation,,thejsector, gear moves in a four step` cycle. For an adding operation, the sector gear is initially disposed in-,its restposition with the cam means positioning the sector gear out of mesh with the numeral wheel driving gear. .During-the lost motion period in the initial portion of the forward stroke of` the `driving member, the cam-means act-to tilt the .Sector gear into mesh with the numeral wheelfdriving gear. After the sector gear is meshed with the numeral wheel driving gear, the drivingk member engages the sector gear, to drive the sector gear, and the enmeshed numeral gear, during the yforward stroke of thedriving member. During the lost motion period in the `initial portion of the return ystroke of thedriving memberthe cam means act to shift the sector gear out `of mesh with the numeral wheel driving gear. The sector gear isithen engaged by the driving member and driven back to its initial position. Since the sector .gear is out .of .mesh with the numeral wheel driving gear during thereturn stroke of the driving member, no motion isimparted yto ,thenumeral `wheel during the return stroke.

When a subtraction operation `is to be performed, f the cammeans arepositioned so that the sector gear is engaged with thenumeral wheel whenthe sector -gearis In this case,` the initial lost motion period of :the forward stroke of the driving member `allowsthe cam means to act to shift the sector lgearlout of mesh with the numeral wheel driving gear before the .sector gear is engaged by the driving member. The .sector gear is driven in the forward stroke out of mesh -with the numeral wheel driving gear. -During the initiallost motion portion -rof the return stroke of the driving-member, the cam means act to shiftthe sector gear 1 into mesh `.with `the numeral wheel driving gear and the return vstroke of the driving member is completed with the sector gear -in mesh withvthe numeral wheel driving.` gear.

By selectivelyy engaging the numeral Wheel driving gear andthe sector gear during one of the forward and return movements of the sector gear, the numeral wheel drivinggear-is driven directly by the sector gear in either of two directions of rotation. i

Means are. provided to hold the numeral wheel against rotation at all times lwhen the sector gear vis not in mesh with the numeral wheel driving gear. ySuitable mechanism also is provided'for initially setting the cam.means to perform either an adding or subtracting operation.

Movement of the sector-gear is controlledvbyae-stop bar which is directly linked to the sector gear. Cooperating cam surfaces are provided upon the keys,vstop bar, and f machine frame -whereby the moving parts are smoothly deceleratedl during the final portions vof the forward ,and return stroke of the mechanism. The cooperatingcam means areso ,oriented as to require a complete-key kactuation before an input, is entered intosthe machine and further assure -a ,complete entryof :the desired input.

Other objects and advantages of my invention will become readily apparent by reference to the following specification taken in connection with the accompanying drawings.

Iii the drawings:

Fig. 1 vis a cross sectional view taken on a substantially vertical plane extending longitudinally of the calculating machine along the mechanism associated with one order of numerals. Certain parts have been partially or entirely omitted for the sake of clarity. v The parts are ldisposed for an adding operation.

' Fig. 2 is a partial cross sectional view taken on a vertical plane slightly closer to the observer than that of means taken on line 5-5 of Fig. l;

Fig. 6 is a view taken on line 6-6 of Fig. 2; Fig. 7is a cross sectional view taken on line '7-7 of Fig. l;

Fig. 8 is a partial cross sectional detail view similar to Fig. 1 showing the mechanism disposed to perform a' subtracting operation;

Fig. 9 is a longitudinal cross sectional view taken in a substantially vertical plane showing mechanism omitted from Fig. l, which mechanism is employed for -setting the machine for addition or subtraction and for clearing the machine. The parts are disposed for an adding operation;

Fig. is a detail view of certain parts shown in Fig. 9i, showing the relationship of these parts when the machine is set for a subtracting operation; and

Fig. l1 is a detail view of portions of the latching tooth operating mechanism.

For purpose of clarity, certain reference numerals have not been applied to parts shown in Figure 1. These reference numerals are applied in Figures 8 and 11 which are detail views corresponding to portions of Figure 1.

Referring to the drawings, in Fig. 1 a vertical cross sectional view of my calculating machine shows the machine case having a base 2 and a cover plate 4. A plurality of slots 6 in cover plate 4 serve to guide the movement of keys 8 employed by the operator to actuate the machine. A ,series of nine keys are employed for each order of numbers which the machine is to accommodate, each of the keys having a button 9 which is numbered in the conventional manner.

The keys 8 have a pair of spaced key posts 10 and 12 y(see Fig. 7) which extend downwardly through slots 6 into the interior of the casing. Key posts 10 and 12 are held in spaced relationship by an upper crosspiece 14 and a lower crosspiece 16. The lower ends of key posts 10 and 12 are guided by slots 18 in plate 20 which is supported from cover plate 4 by posts 22. On the lower side of plate 20, adjacent each of the slots 18, a pair of hook-like projections 24 and a locating notch 26 serve to support a spring 28 which coacts with a pair of 30 notches 30 located in the lower end of legs 10 and 12 of key 8. The spring 28 cooperates with the notches 30 to support the key S in its rest or uppermost position.

Lower crosspiece 16 is notched on its lower edge as at 32 to receive the shaft 34 of double crank 36. Shaft 34 is engaged -by all keys of a given series in this manner and is the rst member of the series of linkages by which the actuation of the keys is transmitted to the indicating mechanism of the machine. Double crank 36, in addi- ,tion to the shaft 34, includes a pair of crank arms 38,

one of which is located at each end of the shaft 34. Double crank 36 is supported within the casing by means of pins 40 which extend from the crank arms 38 and are 4 pivotally suported at each end by plates 42 and 44, respectively. Plates 42 and 44 are respectively supported in slotted projections 46 and 48 which are secured to base member 2.

In addition to engaging slots 32, shaft 34 engages (Figs. 3 `and 4) a slot 5t) in coupling member 52. Coupling member 52 is provided at its upper end with a hole 54 which receives one leg 56 (Fig. 2) of the mainspring 58. Mainspring 58 is located within the casing by the posts 22 (compare Figs. 2 and 6) which engage the torsion coil of spring 58. The other leg 60 of mainspring 58 is hooked over shaft 62 which is xedly mounted within the casing. At its lower end, coupling member 52 has a projection 64 which is adapted to engage the legs of a second torsion spring 66. Motion of the coupling member 52 is transmitted, by means of spring 66, to an arm 68 of sector drive member 70. Y

Sector drive member 70 is pivotally supported by hub 71 upon a xed shaft 72 which extends transversely across the casing of the machine (see Figs. l, 4 and 8). Hub 71 has a projection 73 (Fig. 2) extending outwardly from the hub which serves to locate spring 66 with respect to sector drive member 70. Drive member 70 is integral with the arm 68 and hub 71 (Fig. 4) and extends upwardly yand is then forked to form a generally Y- shaped element. At the upper ends of the arms of the Y are a pair of driving abutments 74 and 76, which are adapted to engage the legs 78 and 8i) of sector gear 82. As shown in Figures l and 8, the arcuate distance between abutments 74 yand 76 is less than the distance along a similar arc between the legs 76 and 80 by the amount L (indicated in Figure 8 only for purposes of clarity). This provides a certain amount of lost motion between driving member 70 and sector gear 82.

At their lower ends, legs 78 and 80 converge to form a hub portion 84 (Fig. 4) which surrounds a part of hub 71 of sector drive member 76. Hub 84 is mounted upon hub 71 for tilting movement about a horizontal axis perpendicular to the axis of shaft 72 as well as for rotatable movement relative to hub 71. At their upper ends, legs 7S and 80 are connected by a gear segment to form a sector gear driving element 82 having teeth adapted to mesh with the teeth of a numeral wheel driving gear 85 which is coupled, by suitable means, to a numeral wheel rotatably supported upon shaft 85a.

Sector gear 82 may be moved into or out of mesh with numeral wheel driving gear 85 by tilting sector gear 82 into or out of the plane of driving gear 85. The tilting action is accomplished by la Y-shaped cam arm 86 which is pivotally mounted upon sector drive member 70 by pivot pin 88. At the upper ends of diverging legs 90 of Y-shaped cam arm 86 a pair of spaced upstanding projections 92 and 94 are otset from each other (see Fig. 5f) so that the forwardmost side of projection 94 is coplanar with the rearwardmost side of projection 92. The inner faces of the projections are relieved so that acute angles 96 and 98 are formed between the respective inner surfaces of projectionsy 94 and 92 and the coplanar surfaces described above. The acute angles define a slot which engages a cam 100 integral with a lug 102 projecting radially inwardly from the inner surface of sector gear 82.

As seen in Figs. 1 and 8, two of these cams 100 are provided on sector gear 82 to engage the two sets of projections which are located on the two arms 90 of Y-shaped cam arm 36. While both of the cams 10i) act simu taneously and in the same manner, the employment of two of the cams 100'assures that the sector gear 82 cannot become cocked out of alignment with respect to driving gear 85 as would be possible were only a single cam v100 employed. The horizontal cross section of cam 100, as seen in Figure 5, is shaped in the form of a winged V having legs 104 and 106. Movement of sector gear 82 relative to the Y-shaped cam arm 86 will cause the cam 100 to pass through the slot between points 96 andv 98., The vslopeof the'r legs 104 and 106 forces the sector gear 82 to move transversely with respect to the Y shaped cam arm .86. This transverse or axial tilting movement of the sector gear 82 causes `che sector gear to move into or out of -the plane of numeral wheel driving ygear '85, thus causing the sector gear 82 and driving gear 85 to mesh or unmesh.

In order to obtain a more rigid and positively acting assembly, the driving abutments 74 and 76 of sector drive member 70 `are connected with a cross bar 108. One face of 'this cross bar slidably engages both legs 90 Y of the Y-shaped cam arm while the opposite face is slidably engaged by projections 110 which extend downwardly from the respective projections 94 of the Yashaped cam arm 86, thus assuring that cam arm 86 is constrained to movement in a plane parallel to that of driving member A70.

Integral with legr 80 of sector gear 82 is arm 112 which is connected by link 114 to stop bar 116.

Stop har 116 extends longitudinally through the space between legs 10 and 12 of all keys within a given group. Stop bar 116 is supported upon lug 118, integral with plate 20 at its forward end, and is further supported and guided in longitudinal movement by fin 120 which cooperates with a slotted post 122 on plate 20 adjacent the rearwardmost end of the stop bar 116. -Stop bar 116 is provided with a series of sets of restraining cam surfaces or abutments 124 and decelerating cam surfaces 126. A restraining cam surface 124 and a decelerating cam surface 126 of suitable configuration are provided for each key of the group. :Restraining cam surfaces 124 and decelerating cam surfaces 126 cooperate with projections 128vwhich are integrally mounted on the legs 10 or 12 of keys 8. The relationship of the cam surfacesl^124aud 126 not only determines .the amount ,of longitudinal movement permitted of stop bar 116 upon the depression of a given key but further serves to restrain and cushion the stroke of stop bar 116.

lIt will be noted that the sets of cam surfaces 124 and 126 for the groups of keys are disposed alternately upon either side of the stop bar 116 to provide a more compact assembly. The projections 128 likewise are alternately mounted upon either post 10 or post 12 of the keys 8. In the embodiment disclosed, the cam surfaces for the keys corresponding to odd numerals are disposed upon the side of the stop member facing the observer in Fig.. l while the cam surfaces for the even numerals are disposed upon the farther side of the stop member. Likewise, the projections 128 for the odd numerals extend inwardly from post 12 of the odd keysv while the projections 128 associated with even numeral keys extend 1nwardly from the post 10.

Movement of stop bar 116 is further cushioned by cooperation of forward lip 130 with cam surface 132 on cover plate 4 and by lower lip 134 cooperating with curved cam surface 136 formed on the forward edge of lug 118.

Operation of stop bar The operation of stop bar 116 will now be described without reference to the action o-f other elements of the actuating mechanism except as they relate to the actual motion of stop bar 116. The operation of the stop bar willbe described with respect to an actuation of the nine key although it is to be understood that a similar action takes place upon the actuation of any other key of the group.

As the nine key (leftmost key in Figure l) is depressed, the crank 34 of the double crank is moved downwardly and starts to actuate the sector gear 82 through the spring 66 and sector drive member 70. However, at the initial stage, the projection 128 on leg 12 of the nine key is moved in front of restraining cam surface 124. This momentarily prohibits forward movement of the stop bar and, since the stop bar 116 is linked through link 114 and arm 112 tosector'gear 82, no movement ,a positive and correct action of the machine.

.ofthe adding machine.

of sector gear 82 can take place at this time. v.This causes the spring 66 to wind up and store energy. As the nine key moves further downward, the upper edge of projection 128 willV eventually clear the leading edge 124a of restraining surface 124. At this moment, the stop bar will be driven forward by the stored energy in spring 66 and the surface 12401 of the restraining cam will ride over the upper surface of projection 128. The forward movement of stop bar 116 will continue until the lower edge of projection 128 is engaged by the decelerating cam surface 126. Due to the curvature of surface 126, the stop-bar 116 will not be brought to an abrupt stop but will be gradually slowed in movement untill the lower edge of projection 128 arrives at a point where the surface 126 becomes vertical. At this moment, thestop bar 116 has reached its forwardmost position.

When `the operator releases the nine key and the sector gear 82 starts to return 'to its original lposition under the influence of main spring 58, the shaft 34 of double cam 36 acts to drive the nine key upward and out of the space between the decelerating cam surface 126 and the trailing edge 12411l ofthe restraining cam. Again, the movement of stop bar 116-is initially restrained until projection 128 on the key clears trailing edge 124b of abutment 124. The nine key is driven upward into its inactive positionand spring-28 engages inthe 30 notches `30 at the lower kends `of the key posts to retain the key in its upwardmost or released position. As the stop bar v116 approaches its rest position, thelower lip 134 engages the curved surface 136 on lug118. and decelerates the stop bar smoothly to its. released position. At the same time, the forward lip 13,0 also engages the decelerating surface 132 on cover plate ,4 to assistthe surface 136 in decelerating the return stroke of stop bar 116.

It will be noted that the foregoing operation insures Itis impossible for the lmachine t0 act until the operator`depresses the key .thenecessary Iamount to insure a complete entry of the desired input. yFurther, it is not possible for the key, and .therefore the driving mechanism to returnto the rest position until the mechanism hasL completed the necessary movements to enter the desired input in the case of addition or are correctly positioned to assure the proper inputpin a subtraction operation.

Add-subtract mechanism The above-description vof the operation ofstop bar 116 has been without reference to the type of operation which is being performed by the machine. As vimplied from the above description, sector4 gear 82 is moved inboth a forward and a return str-oke upon the actuation of any key As has been previously stated, sector gear 82 may be selectively meshed `or unmeshed from the numeral driving wheel 85. To perform an opyeration of addition, the add-subtract mechanism is positioned so that sector gear..82 is meshed with numeral driving wheel 85 during the forward stroke of sector gear 82 and is automatically unmeshed during the return stroke -of sector gear 82. The converse is true-When a subtrac- -ti-on operation is to be performed in that the sector gear `8.2 is unmeshed from numeral wheel driving gear during its forward stroke and is lmoved into mesh with the numeral wheel driving gear 85v during the returnstroke. In addition kto the mechanism for selectively meshing-and `unmeshingsector gear 82 and numeral wheel driving gear 85,1' have lprovided a latching mechanism which acts to lock the numeral wheel driving gear 85 Vagainst rotation when the numeral wheel driving gear is out of mesh with sector gear 82 and to automatically release the numeral Wheel driving gear 85 as sector gear 82 is meshed therewith.

The above operations are performed by the following mechanism most .clearly shown in Figures 9 and 10. An add-subtract key 138 is slidably accommodated by a slot 140 incover member 4. The key-138 has, intermediate its ends, a latching edge 142 which may be engaged with a lip 144 on bar 146 to lock the key 138 in a depressed position as in Figure l0. At its lower end, key 138 is pivotally connected to one arm 147 of a bellcrank 148 by means of pivot 149. Bellcrank 148 is pivotally mounted at 158 to a fixed side plate 151 which is mounted within the casing of the machine. The arm 147 is normally biased to hold key 138 in its uppermost position by tension spring 152 which acts to pivot the bellcrank 148 in a counterclockwise direction against stop 153 -on plate 151. Spring 152 is connected between the opposite arm 154 of bellcrank 148 and fixed side plate 151. Arm 154 of bellcrank 148 is slotted at 156 to receive one end of friction ribbon 158.

Friction ribbon 158 is formed from a length of spring steel stock of rectangular cross-section. The portion of friction ribbon 158 which is received in slot 156 is bent back as at 160 (Figs. 1 and 2) to form a doubled back portion. The free end of the doubled back portion is bent as at 162 to cooperate with a curved offset portion 164 in the main arm of friction ribbon 58 to frictionally mount friction ribbon 158 upon hub 71 of sector drive member 70. The bent portion 160 of friction ribbon 158 is spread apart as at 165 so as to provide a predetermined freedom of movement of friction ribbon 158 between the lower edge 166 of slot 156 and tab 168 which defines the upper limit of slot 156.

A loop 178 is formed at the other end of friction ribbon 158 and receives link 172 which pivotally connects friction ribbon 158 with latching lever 174. Intermediate its ends, latching lever 174 is pivotally mounted upon one arm 176 of a crank which in turn is mounted on side plate 151 (compare Fig. l and Fig. 9). The crank 176 is also involved in the clearing mechanism and, for the purposes of present discussion, will be treated as a fixed pivot. At its upper end, latching lever 174 is provided with `a projecting tooth 178 which is adapted to engage the teeth of numeral wheel driving gear 85.

Returning now to bellcrank 148, arm 154 is further provided with a second slot 180 (Fig. l) which receives a hook-shaped projection 182 of shifting link 184. Shifting link 184 is slidably supported for longitudinal movement in a grooved post 186 which is formed integrally with the base member 2 of the casing of the machine. At the end of shifting link 184 opposite hook 182, a pair of spaced lugs 188 and 190 are disposed. Lugs 188 and 190 are engageable with an extension 192 of the single leg of the Y-shaped cam arm 86.

Operation of add-subtract mechanism In Fig. l, my adding machine is shown with the parts disposed in position to perform an adding operation. The add-subtract key 138 is in its uppermost position and bellcrank 148 is biased by spring 152 to its extreme counterclockwise position, thus positioning the arm 154 of bellcrank 148 in the full line position shown in Fig. 1 (compare common parts in Fig. 9). This position of the arm 154 has moved the shifting link 184 to its extreme righthand position as viewed in Fig. l and the lug 190 abuts against the lower tip 192 of Y-shaped cam arm 86. The abutment of lug 19t) with tip 192 has pivoted cam arm 86 so that the projections 92 and 94 of Y-shaped cam arm 86 are disposed with the points 96 and 98 engaging the notch intermediate the legs 104 and 106 of the V crosssectioned cam 180, as represented by the line A in Fig. 5. At this relative position of cam 100 and projections 92 and 94, sector gear 82 is disposed out of mesh with the numeral wheel driving gear 85.

Friction ribbon 158 is disposed with the lower portion of the bent back end 160 resting against the lower edge 166 of slot 156 in arm 154. With the friction ribbon in this position, loop 170 at the opposite end of friction ribbon 158 is centered at the point B. When friction ribbon 158 is disposed at this position link 172 holds latching lever 174 to its extreme clockwise limit and latching 8 A tooth 178 engages the teeth of numeral wheel driving gear 85 to lock gear 85 against rotation.

Upon the depression of any key, the shaft 34 of double crank 36 pivots downwardly about pins 40. The engagement of shaft 34 in slot 50 of coupling member 52 drives coupling member 52 downwardly against the torsion exerted on leg 54 of mainspring 58. As stated above in the description of the stop bar operation, lug 128 on key 8 engages restraining cam 124 on the stop bar 116 during the initial movement of the key and thus, through link 114, restrains rotary movement of sector gear 82 during the initial motion of key 8. As will be noted in Fig. l,

there is an initial space present between driving abutment 74 and leg 78 of the sector driving gear. This lost motion has been calculated to represent the movement of sector driving member through a 6 degree angle. Motion of coupling member 52 is transmitted to driving element 78 by spring 66. As sector driving element 70 moves through this angle, there is no rotative movement of sector gear 82 since there is no driving abutment present between abutment 74 and leg 78. As the sector driving member 7() moves through this 6 angle, the sector gear 82 is stationary due to the above described holding action of key projection 128, but Y-shaped cam arm 86 is carried with sector driving arm 70 and thus moves relative to sector gear 82. This causes the projections 92 and 94 on cam arm 86 to move relative to the cam 100 which is integral with sector gear 82 and, in the adding operation, the projections 92 and 94 move from their initial position represented by the line A (Fig. 5) along the leg 104 to a position indicated by the line M1. This action of cam arm 86 forces the sector gear to move into the plane of numeral wheel driving gear and thus the teeth of sector gear 82 come into mesh with the teeth of driving gear 85.

As friction ribbon 158 is frictionally coupled to the hub 71 of sector driving member 70, this initial movement causes friction ribbon 158 to move simultaneously with the sector driving member 70. The end 160 of friction ribbon 158 is free to pivot counterclockwise about the shaft 72 to a limit determined by the tab 168. Thus, friction ribbon 158 pivots with driving member 71) in a counterclockwise direction about shaft 72 and the loop moves from position B to a second position C. This action of the friction ribbon moves the link 172 and the link 172 causes latching lever 174 to pivot about arm 176 in a counterclockwise direction, thus disengaging tooth 178 from numeral wheel driving gear 85.

When stop bar 116 allows sector gear 82 to move in a counterclockwis direction as it is driven by the sector driving member 7l), the numeral wheel driving gear 85 is rotated an amo-unt determined by the amount of longitudinal motion permitted of stop bar 116 by the cam surfaces 124 and 126.

The force which acts to return sector gear 82 to its rest position is derived from the energy stored in mainspring `58 during the forward movement of the sector gear. The force stored in mainspring 58 is transmitted to sector gear 82 throrgh coupling member 52, spring 66 and sector drive member '78. Therefore, sector gear 82 cannot begin its return stroke until driving abutment 76 of sector driving member 78 engages the leg 80 of Isector gear 82. Since, at tbe forward limit of the driving stroke,

` the abutment 74 is ragainst leg 78, there is lost motion in movement to return to its original position, there is no driving abutment between driving member 70 and sector gear 82. During the movement of sector driving member y78 in taking up this lost motion, the projections 92 and 94 on the Y-shaped cam arm 86 move relative to sector gear 82 and return from position M1 (Figure 5) to their original position A with respect to cam 100. This relative movement between the sector gear` and the Y-shaped cam arm 86 causes the sector gear 82 to move transversely out of mesh with numeral wheel driving gear 85.

At the same time as the action of the cam 100 is taking place, friction ribbon 158 follows the clockwise movement of hub 71 of sector driving member 70vand the friction ribbon 158 is rotated clockwise so that the loop 170 returns from position C to its original position B, thus causing the latching tooth 178 to return into mesh with the teeth on numeral wheel driving gear 8,5. Upon the completion of the unmeshing of Isector gear 82 and the meshing of latching tooth 178, the driving abutment 76 engages leg 80 of sector gear 82 and, under theinfluence of mainspring 58, sector gear 82 is driven to its original rest position.

If it is desired to perform a subtracting operation, the add-subtract key 138 is depressed until the latching edge 142 is engaged under the lip 144 on bar 146. The depression of key 138 causes bellcrank 148 to rotate clockwise from the full line position shown in Fig. l to the dotted line position shown in Fig. 1l. Clockwise movement of arm 54 acts to shift shifting link 184 from the position shown in Fig. l leftward to Ia position in which the lug 188 on shifting link 184 abut/s l,against the lower tip 192 of Y-shaped cam arm 86 and causes ,a slight clockwise rotation of Y-shaped cam arm 86 about the pivot pin 88 on sector drive member 70. This rotation of Y-shaped cam arm 86 causes the projections 92 and 94 to move relative to carr1100 along leg106 from the position designated by line A in Fig. 5 to the p osition designated M2 in Fig. 5. This causes sector gear 8,2 to be moved into mesh withnumeralwheel driving gear 85.

Simultaneously with the movement ofrshifting link 84, the tab 168 on arm 154 is moved into cont-act with the upper portion of the bent end 160` of friction ribbon 158, and causes a slight clockwiserotation of friction ribbon 158 about the hub 71 of sector drive member 70. This slight clockwise rotation shifts the position of loop 170 from position B to position D. With loop 170 at position D, the latching tooth 178 is engaged with the numera wheel driving gear 85. The situation just described is the only situati-on in which both latching tooth 178 and se-ctor gear S2 are in mesh simultaneously with numeral wheel driving gear 85.

Upon depression of a key, the shaft 34 is moved ydownwardly as before and the motion of shaft 3,4 is transmitted through coupling member 52, spring 66 and arm v 68 t-o the sector drive-member 70 inthe same manner as in the addition operation. The movement of sector drive member 70 to take up the lost motionfbetween driving abutment 74 and `sector gear leg 78 again acts to move the projections 92 and 9.4 on the arms -90 of Y-shaped cam member 86 relative to the `cams 100 on the sector gear. The projections are moved fromtheir original position M2 to the position A of Fig. 5 and in so doing traverse the leg 106 :of` cam, 100. This. movement of the projections 92 and 94 acts through the` cam 100 to disengage sector gear 82 from mesh with-numeral wheel driving gear 85 during the forward stroke of sector gear 82. At the same time the action of unmeshing of ysector gear S2 from gear 85 is taking place, .the following action takes place with the friction ribbon 15,8.

The counterclockwise movement of sector driving member 70 causes friction ribbon 158 to attempt to follow the counterclockwise movement of hub 71. However, the end 160 of friction ribobn 158 abuts the upper limit of its stroke as defined by the tab l168 andk friction ribbon 158 is thus prevented from rotating. in a counterclockwise direction. The frictional grip ,of curved portions 162 and 164 is not so tight as to prohibit the slight relative movement between hub 71 and friction ribbon 128 which occurs at this time. Thus, no action ttakes place with latching lever 174 and the tooth 178` remains in mesh with numeral wheel driving gear 85to1lock gear 85 against rotation.

The sector gear $2 then completes its forward stroke. At the beginning of the return lstroke, there is again the 6 degrees of lost motion which must be taken up between abutment 76 and leg 80 of sector gear 82. As sector driving member 70 rotates in a clockwise direction to take up this lost motion, the projections 92 on Y-shaped cam member 86 move from the position A out along leg 106 of cam 100 and return to the position M2 causing sector gear 82 .to mesh `with gear 85 to drive the gear as the sector gear completes its return stroke.

The initialclockwise rotation :of sector driving member 70 in accomplishing the ,above described camming action also causes friction ribbon 158 to rotate in a clockwise direction along with the hub 71 of member 70. The clockwise rotation of the friction ribbon 158 is permitted since there is sufficient space between the bottom of the portion 160 and the bottom 166 of slot 156. Thus, the friction ribbon 158 is permitted to rotate in a clockwise direction and the loop 1704 moves upwardly from position D to position E. The rotation of friction ribbon 158 from position D to position E causes link 172 to pull latching lever 174 in a counterclockwise direction about the pivot 176, thus disengaging latching tooth 178 from numeral wheel driving gear 85. At the completion of the operation, the friction ribbon 158 will remain with its loop in position E and the latching tooth 178 out of engagement with gear 85. However, during the initial stage of the next succeeding subtraction operation, the loop 170 will again be moved back to position D.

The add-subtract .key 138 may be returned to its original luppermost position by a rearward movement of clearing lever 194 which moves a sufficient distance to release the latch 142 from beneath the lip 144.

Clearingy mechanism Upon the completion of any given calculation, it is desirable to return the numeral wheels to their zero position. .This is accomplished by a clearing mechanism constructed in the following manner (see Figs. 9 and 10).

The clearing mechanism is actuated by clearing lever 194 which passes through a slot 195 in cover plate 4 immediately to the rear of the location of subtracting key 138. `Clearing lever 194 is pivotally mounted at its lower end upon a pivot 196 fixedly secured to the base 2. Intermediate the ends of clearing lever 194, the clearing lever is pivotally connected at 198 to bar 146. Clearing lever 194, and consequently bar 146, are constantly biased to their leftwardm'ost position as viewed in Fig. 9 by tension spring 200 which is connected between lever 194 and side plate 151.

Longitudinal motion of bar 146 is guided by cooperation Iof a slot 202 vin bar 146 and a shouldered pin 204 which projects from plate 151 through slot 202. Intermediate the ends of bar 146, a link 206 is pivotally connected at one end by means kof a pin 208 mounted on bar 146. At its other end, link 206 is pivotally connected at 212 to crank link 210. The link 210 is fixedly connected at its other end to one arm 214 of a crank 216. The lower arm 218 of crank 216 is secured by loop 220 to the lower end of clearing rake 222.

Rake 222 is yprovided with an upstanding ear 224 midway of its length. The ear 224 engages one arrn of a crank 228 which is pivotally mounted at its `other end in side plate 151. At its upper end, rake 222 is bent as at 238 to form a rake tooth 232. Rake tooth 232 is so disposed as to be engageable with projections such as 234 and 236 which are integrally mounted upon the 'numeral wheel.

Movement of clearing lever 194 from the full line position shown in Fig. 9 tothe line K in Fig. 9 actuates the clearing rake 232 through bar 146, link 206, link `210, crank 216, and crank 228 `to move from. the posi- `tion shown from the full line position shown in Fig. 9

11 to the dotted line position of Fig. 9. In moving from the full line to the dotted line position, the rake tooth 232 will engage a projection such as 234 and move the projection into the position occupied by projection 236 in Fig. 9. Further movement of the rake is prohibited at this point by the engagement of the heel 23S of the rake with the next succeeding projection 236. The movement of numeral wheel occasioned by the abutment of the rake tooth 232 with a projection 234 upon the numeral wheel drives the numeral wheel to a position corresponding to zero setting.

It is readily apparent that no movement of the numeral wheel will be possible unless the latching tooth 178 is disengaged from the numeral wheel driving gear SS. Disengagement of the latching tooth is accomplished in the following manner. A slot 240 is provided adjacent the leftwardmost end of bar 146 as viewed in Fig. 8. The notch 240 is adapted to engage an arm 242 of a bellcrank which is pivotally supported from side plate 151 by an arm 244. The arm 244 forms one arm of a crank and is integrally connected by arm 245 with the crank 176 upon which the latching lever 174 is pivotally mounted. Integral with arm 242 is the remaining arm 246 of the last mentioned bellcrank. Arm 246 is biased in its unactivated position against a fixed stop 248 on side plate 151 by means of spring 250 which is connected between the arm 246 and side plate 151. Movement of the clearing lever 194 from its full line position to line K in Fig. 9 causes the bar 146 to move to the right. As bar 146 moves to the right, the notch 240 engages the arm 242 and causes the arm 242 to rotate in a clockwise direction as viewed in Fig. 8. The clockwise movement of arm 242 is directly applied to the arm 244 of crank 245 and causes the arm 176 to move leftward in a clockwise direction. Since the lower end of latching lever 174 is restrained from movement in this direction by link 172, the arm 176 causes the latching lever 174 to pivot about the connection between 174 and 172 in a counterclockwise direction, thus disengaging latching tooth 178 from numeral wheel driving gear 85.

When the machine :is set to perform a subtracting operation, the sector gear 82 is in mesh with numeral wheel driving gear 85 in the rest position and would prevent any movement of the numeral wheel as would be required to clear the machine.

In order to prevent injury to the machine by an inadvertent attempt of the operator to clear the machine when the machine was set for a subtracting operation, two safeguards have been provided.

The first is the utilization of the initial movement of the clearing lever 194 to unlatch the add-subtract key 138 from its subtract (depressed) position by causing the release of latching edge 142 from beneath lip 144. The

release of latching edge 142 permits the add-subtract key 133 to return to its add (uppermost) position by action of tension spring 152 on bellcrank 150. Upon return of key 138 to its uppermost or add position, the action of the machine would be to unmesh sector gear 82 from numeral wheel driving gear S and to engage latching lever 174 with gear 85. Latching lever 174 is then disengaged in the manner described above.

However, a sudden actuation of clearing lever 194 might canse the clearing rake 222 to attempt to clear the mach-ine before sector gear 82 was fully disengaged from `driving gear S5. A sudden actuation of this type would obviously cause injury to the machine and I have eliminated the possibility of such an occurrence by forming a projection 239 on bar 146.

With key 133 in the subtract (or lower) position, movement of clearing lever 194 and bar 146 to the right, as viewed in Figure 9, the lip 144 releases latching edge 142. Further continuous movement of bar 146 to the right is prohibited until latching edge 142 -is moved above the path of projection 239. The linkages concerned are so arranged that a complete disengagement of sector gear 82 and latching lever 174 from driving gear 85 has occurred when latching edge 142 has cleared projection 239. When the operator wishes to change from a subtraction operation to an addition operation without first clearing the machine, `a quick light touch on the clearing lever 194 will release lever 138 for movement upwardly into the addition position.

It will be apparent to those skilled in the art that my invention is capable of modifications. The specific structural embodiment described above is to be considered as an exemplary form and the true scope of my invention is that dened in the following claims.

I claim:

l. A calculating machine comprising a rotatable numeral wheel, means supporting said numeral wheel for rotation, a driving element movable from a rest position in a sequential series lof movements consisting of 'a first shifting movement, a forward stroke, a second shifting movement in a direction opposite to the direction of said first shifting movement and a return stroke, one of said strokes being along a first path wherein said driving element is engaged with said numeral wheel to rotate said numeral wheel and the yother of said strokes being lalong a second path wherein said driving element is disengaged from said numeral wheel, said shifting movements shifting said driving element between said paths, first means engageable with said driving element for driving said driving element in said forward and said return stroke, said first means having a predetermined lost motion movement prior to engagement with said driving element on each of :said strokes, second means mounted on said first means vand engageable with said driving element to impart one of said shifting movements to said driving element during each of the lost motion movements of said first means, and means to selectively establish said rest position in either of said first and second paths.

2. A calculating machine according to claim 1 having a biasing means connected to said first means and biasing said first means to said rest position.

3. A calculating machine according to claim l having means engageable with said numeral wheel to prevent rotation of said numeral wheel when said numeral wheel is not engaged by said driving element.

4. A calculating machine comprising a numeral wheel including a gear, means supporting said numeral wheel for rotation, a driving gear positioned adjacent to said numeral wheel and tiltable into mesh with said numeral wheel gear to drive said numeral wheel gear and rotate said numeral wheel, means supporting said driving gear for both tilting and driving movement, first means engageable with said driving gear to move said driving gear to drive said numeral wheel gear, and second means controlled by said first means and engageable with said driving gear to tilt said `driving gear into mesh with said numeral wheel gear upon relative movement between said first means and said driving gear prior to driving of said numeral wheel gear.

5. A calculating machine comprising a rotatable numeral wheel including .a gear, said numeral wheel being rotated when said gear is driven, means supporting said numeral wheel for rotation, a shiftable -driving gear positioned -adjacent to said numeral wheel and movable in a series of movements including a forward stroke and a return stroke, means supporting said driving gear for said shifting and said movements, first means engageable with said driving gear to move said driving gear first in said forward stroke and `then in said return stroke, said driving gear meshing with said numeral wheel gear selectively either on the forward stroke of the driving gear or the return stroke of the -driving gear to rotate said numeral wheel, and second means engageable with said driving gear upon relative movement between said first means and said driving gear to shift said driving gear so that said driving gear either meshes with said numeral wheel gear on said forward stroke and by-passes said 13 numeral wheel gear on said return stroke or by-passes said numeral wheel gear `on said forward stroke and meshes with said numeral wheel gear on said return stroke.

6. A calculating machine comprising a rotatable numeral wheel, means supporting said numeral wheel for rotation, a driving element positioned adjacent to and engageable with said numeral wheel to rotate said numeral wheel, said driving element being normally in a position of rest but being movable from and then baci;Av to said position of rest in a series of movements including a forward movement and a return movement, a movement controlling member connected to said driving element, said controlling member being movable with said driving element during said forward movement and said return movement, a depressible key, means connecting said key to said driving element to cause forward movemeut of said driving element on depression of said key and return movement of said driving element on release of said key, a first cam means located on said controlling member, means on said depres'sible key and engageable by said first cam means to cushion forward movement of said driving element, a second cam means, and means on said controlling member engageable with said second cam means to cushion return movement of said driving element.

7. A calculating machine comprising a rotatable numeral wheel, means supporting said numeral wheel for rotation, a driving element positioned adjacent to and engageable with said numeral wheel to rotate said numeral wheel, a movement controlling member connected to said driving element, said driving element and said controlling member being movable together, a depressible key, means connecting said key to said driving element and operable upon depression of said key to move said driving element, cam means on said controlling member, and means on said key engageable by said cam means to cushion movement of said driving element following depression of said key.

8. In a calculating machine, a depressible key, said key being returnable when released, a stop bar positioned adjacent to and extending beneath the said depressible key, said stop bar being movable in a series of movements including a forward movement and a return movement, means connected to said stop bar to move said stop bar in said forward movement, said last named means being operable upon depression of said key, a sloped surface on said stop bar, a projection on said key, said projection being engageable by said sloped surface to cushion forward movement of s'aid stop bar upon depression of said key, said sloped surface urging said key upwardly when said projection engages said surface, and an abutment on said stop bar adjacent said sloped surface, `said projection on said key being engageable by said abutment to prevent continued return movement of said stop bar until said projection clears said abutment.

9. in a calculating machine, a depressi'ole key, means engaging said key and biasing it against depression, an elongated stop bar positioned adjacent to and extending beneath said key, said stop bar being movable longitudinally from a position of rest to another position and then back to said position of rest, means connected to said stop bar and operable to move said stop bar following movement of said key, said stop bar having walls defining a passage extending lengthwise with respect to said stop bar, said passage having an entrance and an exit, said entrance being defined in part by a leading edge of an abutment member on said stop bar and said exit being defined in part by a trailing edge on said abutment member, and a projection on said key positioned above said passage entrance when said stop bar is in its rest position, said projection being movable into said entrance upon depression of said key, said leading edge of said abutment preventing continued movement oi said stop bar from said position of rest until `said leading edge of said abutment clears said projection, said abutment riding over saidy projection during movement of said stop bar from said position of rest, and said trailing edge of said yabutment preventing continued movement of said stop bar back to said position of rest until said projection clears said trailing edge.

References Cited in the file of this patent UNITED STATES PATENTS 1,246,087 Gooch NOV. 13, 1917 2,165,288 Mills July l1, 1939 2,273,237 Walter Feb. 17, 1942 2,356,714 Webb Aug. 22, 1944 FORElGN PATENTS 175,395 Austria July 10, 1953 

